Remove values from select list based on condition

Question

I have the following in the page

<select name="val" size="1" >
<option value="A">Apple</option>
<option value="C">Cars</option>
<option value="H">Honda</option>
<option value="F">Fiat</option>
<option value="I">Indigo</option>                    
</select> 

I would like to remove certain values from my select if certain conditions are true.

E.g

if(frm.product.value=="F"){
  // remove Apple and Cars from the select list
}

How can I do this using javascript

Answer 1

The index I will change as soon as it removes the 1st element. This code will remove values 52-140 from wifi channel combo box

obj = document.getElementById("id");
if (obj)
{
        var l = obj.length;
        for (var i=0; i < l; i++)
        {
            var channel = obj.options[i].value;

            if ( channel >= 52 &&  channel <= 140 )
            {
                obj.remove(i);
                i--;//after remove the length will decrease by 1 
            }
        }
    }

Answer 2

For clear all options en Important en FOR : remove(0) - Important: 0

var select = document.getElementById("element_select");
var length = select.length;
for (i = 0; i < length; i++) {
     select.remove(0);
 //  or
 //  select.options[0] = null;
} 

Answer 3

Check the JQuery solution here

$("#selectBox option[value='option1']").remove();

Answer 4

As some mentioned the length of the select element decreases when removing an option. If you just want to remove one option this is not an issue but if you intend to remove several options you could get into problems. Some suggested to decrease the index manually when removing an option. In my opinion manually decreasing an index inside a for loop is not a good idea. This is why I would suggest a slightly different for loop where we iterate through all options from behind.

var selectElement = document.getElementById("selectId");

for (var i = selectElement.length - 1; i >= 0; i--){
  if (someCondition) {
    selectElement.remove(i);
  }
}

If you want to remove all options you can do something like this.

var selectElement = document.getElementById("selectId");

while (selectElement.length > 0) {
  selectElement.remove(0);
}

Answer 5

Give an id for the select object like this:

<select id="mySelect" name="val" size="1" >
    <option value="A">Apple</option>
    <option value="C">Cars</option>
    <option value="H">Honda</option>
    <option value="F">Fiat</option>
    <option value="I">Indigo</option>                    
</select> 

You can do it in pure JavaScript:

var selectobject = document.getElementById("mySelect");
for (var i=0; i<selectobject.length; i++) {
    if (selectobject.options[i].value == 'A')
        selectobject.remove(i);
}

But - as the other answers suggest - it's a lot easier to use jQuery or some other JS library.

Answer 6

if(frm.product.value=="F"){
    var select = document.getElementsByName('val')[0];
    select.remove(0);
    select.remove(1);
}